It 'works' because when you connect things in parallel, you add the currents. So 40 LEDs in parallel with an adapter than can supply 350ma means each LED gets less than 9ma, so it doesn't blow. You just have to make sure there are enough connected at all times so that the total current divided by the number of LEDs is less thant he LED's rating, which is the maximum it can sustain.
It gets a little more complicated because you're alway workign against the internal resistence of the power supply so a different type of power supply but with the same ratings may not work. Somethign like a battery, with a high current surge, would also not typically work.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
I am using wall adapters that I find in bins at thrift shops like Good Will. I get them for 50 cents each in most cases. All of them have their output levels listed on the plug.
The LEDs I use draw 2.8-3.5 VDC each so I am using 3 VDC 200-300 MA adapters. Always make sure you have a few bulbs wired up or use a resistor when testing the bulbs. I have one 3 VDC adapter powering over 40 bulbs when wired in parallel. If you run them in series you will need a 12V adapter to run less than 10 or so. Once you have a full string of bulbs wired I have found that resistors are not needed. If running in parallel all the bulbs must run on the same voltage. If running in series you can mix and match but you will be really limited in how many you can use with one 12V adapter since the voltage load increases with each bulb. For instance I have one building wired in series which requires its own 30V adapter. I avoid running in series as much as possible but some times space constraints make it necessary.
I use Miniatronics bulbs and ones from that auction site. All of them are 1.5 to 1.8 mm. Blue and white LEDs typically require more voltage than other colors so I run those on separate adapters or in series if mixed with other colors. I use mostly white, warm white, yellow and orange bulbs.
One important rule I keep that helps is if the bulbs or adapter are running warmer than normal its time to cut back the power. Cool running bulbs and adapters should last a long time. I sometimes leave mine on for days at a time.
Hope this helps as my electronics knowledge is limited but I know what works for me and I have yet to blow out any LEDs matched with the right adapters.
Groove Rider:
Can you tell us what you are using for a power supply. Since I don't see any resistors I assume it must be low voltage. Also, what type of LEDs are you using and what is your source? I am in the process of lighting several buildings and I have been using LEDs with a 12 volt power supply so every one has to have a resistor in series. Your method looks to be a lot simpler.
Your advise is very much appreciated.
Dave
I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!
I guess it depends on how serious you want to be with your lighting. The easiest way is slap up a bulb or two for each building. I like to separate the floors and make interior rooms as it's much more realistic looking IMO.
I use mostly LEDs and some regular bulbs on my N scale layout. I developed some relatively easy techniques using brass rod and tubing.
Here are some pics: (note the interiors still need to be detailed with people, etc.)
And here are a few pics of the results. Keep in mind the camera makes some of them look burned out but that is not the case seen in person.
AlecWilliamFry Hello there, I wanted to do some lighting within some of my HO scale buildings and was wondering who makes the simplest system for doing so. Your help is much appreciated. Regards, Alec
Hello there,
I wanted to do some lighting within some of my HO scale buildings and was wondering who makes the simplest system for doing so.
Your help is much appreciated.
Regards,
Alec
gatrhumpy Also, to prevent light from escaping the house, I paint the inside of the walls black and seal the edges with caulk. Finally, I decorate and paint near large windows where one can see inside the building. I have even gone so far as to place a human figure in the window opening. It works very well.
Very good suggestions. I look for structures with large windows just so that I can add interiors. They don't have to be elaborate, and they certainly don't have to be expensive. This is the City Classics "West End Market" kit:
A couple of things to note here. I used cardstock (heavy paper from Staples) and printed the interior walls on my computer. Then I cut the printouts to size and glued them to the plastic. These are fairly thick-walled models, so leakage through the walls is minimal, but adding the cardstock blocks it even better.
The floor and the shelves, likewise, are printed on cardstock. I bought a number of these lamp-and-socket sets from IHC a number of years back. I've mounted the lamp so that it is not visible through the windows. I've found that to be important. You can used cardstock view-blocks to accomplish this, if the interior doesn't have a good place to hide the bulb.
A few Preiser figures complete the scene. From the outside, the illusion of a busy market is pretty good.
It takes an iron man to play with a toy iron horse.
Alec, others have made some fine suggestions so far. However, I went one step further and planned for replaceability in the future in case a bulb burned out. What I did was to get some micro connectors that unplug when you need them too. That way, whenever a bulb burns out (none have so far), I can lift the building, take out the old bulb, and replace it very easily.
The micro connectors are about $2 each, but I think are well worth the trouble.
Also, to prevent light from escaping the house, I paint the inside of the walls black and seal the edges with caulk. Finally, I decorate and paint near large windows where one can see inside the building. I have even gone so far as to place a human figure in the window opening. It works very well.
I use batteries for some and wall warts for others. Dedicated wall warts seem better to me than the DC terminal on the power pac. I found small AA bat pacs at a surplus store that holds enough to get 12 volts. Befor that I built some using a 9v and two 1 1/2 v. They worked but were akward. They were portable though.
Which type of DC power source should I use? Will you please send me an example.
Thanks,
Lately there has been a move to using LED lights. They last significantly longer and are just as easy to install.
A good type are actually the one's used for LED christmas lights. they have a cone in them that disperses the light 360 degrees.
good Luck
Springfield PA
Model Power has some self adhesive lights that you just stick to your building and run the wires to a DC source.
The simplest systems , you make your self. I have stayed away from LED just because they are complicated.
1. Get some small 12v - 14v bulbs from your LHS
2. Glue them in your structures with Thick super glue.
3. Run all the wires together and solder them in pairs.
4. I then soldered the pairs to male plugs I got at a surplus store.
5. Get a 12 v walwart. I got mine at the same surplus store.
6. I then made a terminal strip with female plugs that I soldered to the walwart.
6. I can then plug the buildings to the terminal strip and I have lights.
7. I put a SPST switch between the walwart and the terminal strip so I could turn the whole thing off.
It was easy and simple.